124 HEPBURN— BIOCHEMICAL STUDIES OF 



Sufficient liquor was not always obtained from a single pitcher 

 to permit plating on all six media. However, a general tendency 

 was noted that, when the microorganisms present in the pitcher 

 liquor grew on one of these media, they grew on all the media, and 

 usually exerted a visible digestive action on all the proteins. 



Production of Basic Compounds. — A study was also made of 

 the formation of basic compounds by the action of the micro- 

 organisms on simple organic compounds, which served as the sole 

 source of carbon and nitrogen in the medium. The solid media 

 were prepared by addition to the stock solution of inorganic salts 

 of 2 per cent, of agar, 0.5 per cent, by volume of a 2 per cent, 

 solution of rosolic acid in 60 per cent, alcohol, and one of the fol- 

 lowing compounds: glycocoll (an amino acid), acetamide (an acid 

 amide), asparagin (which is both an amino acid and an acid amide), 

 ammonium lactate (an ammonium salt of an organic acid). One 

 per cent, of asparagin was used, the other compounds in molecular 

 concentration equal to that of the asparagin. These media were 

 always sterilized by the discontinuous method. Plating experi- 

 ments were made, sowing i c.c. of pitcher liquor in each plate. The 

 production of basic compounds by microorganisms growing on these 

 media was indicated by a red color of the medium beneath and 

 surrounding the colony. Sterile plates were always poured as con- 

 trols, to be used in determining the changes in color of the experi- 

 ments proper. 



The number of experiments plated on each of these media was : 



Glycocoll rosolic acid agar 7 experipients. 



Acetamide rosolic acid agar 7 experiments. 



Asparagin rosolic acid agar 22 experiments. 



Ammonium lactate rosolic acid agar 7 experiments. 



The period of incubation was from ten days to a fortnight, the 

 plates being inspected at intervals until further observation was 

 rendered useless by drying of the media. Colonies developed in all 

 save one of the experiments, the sole exception being a plate of 

 glycocoll rosolic acid agar. The colonies were usually apparent by 

 the third day ; though, in a few instances, they grew so slowly that 

 they became apparent only at the tenth day. The organisms always 



